Xxii - INTRODUCTION. 
The Coniston limestone appears to be the exact equivalent of the Bala limestone both in 
its mineral type and in its group of fossils; and the Coniston flagstone seems to represent 
(in a very degenerate form) the slate, flags, grits, shelly sandstones, and coarse conglomerates 
which in North and South Wales overlie the Bala limestone and the Llandeilo calcareous 
flagstone. 
( A thick group composed of hard siliceous sandstone, in some places of very 
“ coarse texture, and passing into a conglomerate form. It is very sterile of 
fossils, and the few which have been found give no decisive evidence as to 
its epoch. Without any obvious discordance of position it marks the com- 
mencement of a great change of mineralogical type; and immediately above 
it we find the commencement of a newer Fauna. It much resembles the 
sterile portions of the May Hill sandstone, and it appears to have the same 
place in the general series. 
‘a. Lower Ireleth slate ; coarse, and seldom applied to use as roofing-slate. 
b. 
C: 
d 
(@ 
b. 
1. Coniston grits ..... J 
Treleth limestone ; concretionary and discontinuous; a few very obscure 
fossils. 
Upper Ireleth slate. Many subordinate beds of grit, and many alterna- 
tions ; largely quarried. 
Coarse slate and grit ; seldom quarried for roofing-slate *. 
A great group of flags, grits, &c.; beds without good transverse cleavage. 
North side of Kendal Fell and Valley of the Kent. Fossils abundant ; 
prevailing type Lower Ludlow. 
Grit, sometimes in thick beds, and of coarse texture ; flagstone; bands of 
coarse slate, generally without transverse cleavage ; fossils in certain 
beds abundant, and of the Upper Ludlow type. The moors S. E. of Kendal. 
c. Tilestone, resembling that described in the “Silurian System ;” fossils 
abundant, and of the Upper Ludlow type. 
2. Treleth slate-group of 
great thickness* .. . 
Equivalents of Silurian Series. 
3., Kendal group ..... 
Collectively, the above series (from the Coniston grits to the Kendal group inclusive) is of 
very great thickness; yet, being almost without any subordinate beds of limestone, it is not so 
prolific of fossils as the corresponding groups in Siluria. 
There are in the Woodwardian Museum, I believe, 166 ascertained species collected 
from the groups between the Skiddaw slate and the Tilestone inclusive; and when these species 
are divided into tivo groups—the upper representing all the known fossil species down to the 
base of the Coniston grits, and the Jower, all the known species below the Coniston grits—the 
two groups are found to have but five species in common. In other words, between the Cambrian 
and Silurian series in the North of England, there are not more than about three per cent. 
taken as a key, the confusion among the groups was inexplicable; simply because the key was false to nature. But the 
moment the so-called “Silurian key” was thrown aside, the Coniston limestone naturally fell into the place I had first 
given to it. It became the equivalent of the Bala limestone; and the whole succession became, once more, perfectly 
natural, both on physical and palzontological grounds. 
* The Ireleth slate-group is spread over a wide extent of country, and is of great thickness, and its fossils, though 
generally rare, are of the Wenlock type. In the sub-group (d) some of the fossils seem to belong rather to the Ludlow 
rocks; among which the Hemithyris navicula is in great abundance. This sub-group seems to pass into, and to be blended 
with, the sub-group (a) of the higher, or Kendal, group. 
